I was going to say orange, until I read "Crafty's" reply & realized I also don't have any solid black (I DO have some cute prints on black). My grandson recently asked me to make a quilt for him. He picked out the pattern & asked that I include orange (orange & black are his school colors) - he was very specific about what type of prints -- lots of geometrics, no dainty yellows or greens & definitely no florals! So I found a wonderful black paisley, 108", for the backing & will incorporate some onto the front. So now I have some oranges, golds, maroons, browns & lots of geometrics to cut up! A few yrs ago I would have said lime green, then a grandaughter asked for it in a quilt!